[seL4] Re: sel4-sys support

On Thu, Dec 16, 2021 at 11:36 AM Sam Leffler wrote:

[Karol is working with me on this so hopefully it's ok to interject]

On Wed, Dec 15, 2021 at 3:40 PM Kent Mcleod wrote:

...

On Thu, Dec 16, 2021 at 1:20 AM wrote:

...

Hi All,

We’ve been working on reviving the sel4-sys Rust crate and getting it usable again. Currently, we have it working correctly with RISC-V, we’re working on ARM (including aarch64) and X86. We’d like to contribute this work, but to have it landed we need to extend the test suite to include crate tests - especially the syscalls API.

During the build, the crate generates the syscalls functions accessible from Rust code based on seL4 config.

We use standard sel4test-tests suite to handle the tests:

* We build the crate as static library * Sel4test is built with `-DLibSel4FunctionAttributes=public` and while linking we overwrite the original symbols with the ones from a static library from the crate

This allows us to run the standard test suite against Rust syscall stubs.

For now the crate generates the syscall stubs with Rust flavor, so functions signatures between Rust and C do not match. To handle this we additionally generate a thin glue code adopting Rust signatures to the C ones.

We generate the Rust syscalls with a slightly modified version of the `syscall_stub_gen.py` script - we copied it into the crate’s codebase. Copying the code doesn’t seem to be the best idea - we’d need to maintain the code in both places - seL4 kernel and the crate.

We’d like to merge the Rust generator with the current set of tools - is this something you’d be willing to land in the kernel code? If not, how would you see the way forward here?

Hi, Thanks for making this proposal!

Rust syscall binding support is something that we'd like to support. Are you able to make a pull-request with the changes to `syscall_stub_gen.py`? Depending on the changes we'd probably be happy to merge them upstream.

The current code hacks Rust in as a parallel branch to C (i.e. throughout the code there are "if C then elif Rust then..."). Karol wants to restructure the python to cleanly support multiple languages before submitting.

A link to a public branch to look at would be fine initially too. Just to check that there aren't any obvious incompatibility issues.

...

Do you also hope to merge the sel4test changes upstream? I think this would require more discussion as the sel4-sys crate was created by the Robigalia project and isn't maintained by the seL4 foundation so we wouldn't be able to easily maintain that functionality to keep the new parts of sel4test working.

Yes, that is a goal too. Ideally we'd like Rust support to track seL4 kernel changes. Note the scope of sel4-sys is growing as it gets pulled in for more uses and some decisions I made may be controversial (e.g. I've made Rust api bindings return a new seL4_Result instead of seL4_Error).

Does this mean you are expecting to publish your updates under the sel4-sys crate on crates.io? Is that something that's already been coordinated with the Robigalia project? The readme at the moment says that it has been "yanked"

...

...

Thanks and best regards Karol _______________________________________________ Devel mailing list -- devel@sel4.systems To unsubscribe send an email to devel-leave@sel4.systems

---

Devel mailing list -- devel@sel4.systems To unsubscribe send an email to devel-leave@sel4.systems